Permafrost carbon feedback (PCF) modeling has focused on gradual thaw of near-surface permafrost leading to enhanced carbon dioxide and methane emissions that accelerate global climate warming. These state-of-the-art land models have yet to incorporate deeper, abrupt thaw in the PCF. Here we use model data, supported by field observations, radiocarbon dating, and remote sensing, to show that methane and carbon dioxide emissions from abrupt thaw beneath thermokarst lakes will more than double radiative forcing from circumpolar permafrost-soil carbon fluxes this century. Abrupt thaw lake emissions are similar under moderate and high representative concentration pathways (RCP4.5 and RCP8.5), but their relative contribution to the PCF is much larger under the moderate warming scenario. Abrupt thaw accelerates mobilization of deeply frozen, ancient carbon, increasing 14C-depleted permafrost soil carbon emissions by ~125-190% compared to gradual thaw alone. These findings demonstrate the need to incorporate abrupt thaw processes in earth system models for more comprehensive projection of the PCF this century.
Recent rapid Arctic sea-ice reduction has been well documented in observations, reconstructions and model simulations. However, the rate of sea ice loss is highly variable in both time and space. The western Arctic has seen the fastest sea-ice decline, with substantial interannual and decadal variability, but the underlying mechanism remains unclear. Here we demonstrate, through both observations and model simulations, that the Pacific North American (PNA) pattern is an important driver of western Arctic sea-ice variability, accounting for more than 25% of the interannual variance. Our results suggest that the recent persistent positive PNA pattern has led to increased heat and moisture fluxes from local processes and from advection of North Pacific airmasses into the western Arctic. These changes have increased lower-tropospheric temperature, humidity and downwelling longwave radiation in the western Arctic, accelerating sea-ice decline. Our results indicate that the PNA pattern is important for projections of Arctic climate changes, and that greenhouse warming and the resultant persistent positive PNA trend is likely to increase Arctic sea-ice loss.
It is predicted that Arctic Ocean acidity will increase during the next century as a result of carbon dioxide accumulation in the atmosphere and migration into ocean waters. This change has implications for sound transmission because low-pH seawater absorbs less sound than high-pH water. Altered pH will affect sound in the 0.3-10?kHz range if the criterion is met that absorption is the primary cause of attenuation, rather than the alternatives of loss in the ice or seabed. Recent work has exploited sound that meets the criterion, sound trapped in a Beaufort Sea duct composed of Pacific Winter Water underlying Pacific Summer Water. Arctic pH is expected to drop from 8.1 to 7.9 (approximately) over the next 30-50?yr, and effects of this chemical alteration on the intensity levels of this ducted sound, and on noise, are examined here. Sound near 900?Hz is predicted to undergo the greatest change, traveling up to 38% further. At ranges of 100-300?km, sound levels from a source in the duct may increase by 7?dB or more. Noise would also increase, but noise is ducted less efficiently, with the result that 1?kHz noise is predicted to rise approximately 0.5?dB.
Environmental Microbiology Laboratory, Environmental Engineering Institute, School of Architecture, Civil and Environmental Engineering, École Polytechnique Fédérale de Lausanne, 1015, Lausanne, Switzerland. firstname.lastname@example.org.
The deep terrestrial subsurface remains an environment where there is limited understanding of the extant microbial metabolisms. At Olkiluoto, Finland, a deep geological repository is under construction for the final storage of spent nuclear fuel. It is therefore critical to evaluate the potential impact microbial metabolism, including sulfide generation, could have upon the safety of the repository. We investigated a deep groundwater where sulfate is present, but groundwater geochemistry suggests limited microbial sulfate-reducing activity. Examination of the microbial community at the genome-level revealed microorganisms with the metabolic capacity for both oxidative and reductive sulfur transformations. Deltaproteobacteria are shown to have the genetic capacity for sulfate reduction and possibly sulfur disproportionation, while Rhizobiaceae, Rhodocyclaceae, Sideroxydans, and Sulfurimonas oxidize reduced sulfur compounds. Further examination of the proteome confirmed an active sulfur cycle, serving for microbial energy generation and growth. Our results reveal that this sulfide-poor groundwater harbors an active microbial community of sulfate-reducing and sulfide-oxidizing bacteria, together mediating a sulfur cycle that remained undetected by geochemical monitoring alone. The ability of sulfide-oxidizing bacteria to limit the accumulation of sulfide was further demonstrated in groundwater incubations and highlights a potential sink for sulfide that could be beneficial for geological repository safety.
Given the high rates for substance use among women and men of childbearing age, perinatal and early childhood home-visiting programs serving tribal communities must consider how they will address substance-use problems among the families they support. In this study, we explored the approaches to identifying and addressing family-based substance-use problems that were implemented by nine home-visiting programs serving American Indian/Alaska Native (AI/AN) communities that are funded through the federal Tribal Maternal, Infant, and Early Childhood Home Visiting Program (Tribal MIECHV). These programs demonstrated a high awareness of substance-use problems and took concrete action to address them above and beyond that included in the home-visiting model they used. All nine programs reported that they provided substance-use preventive services and screened for substance-use problems. While all programs referred to substance-use treatment programs when needed, in six programs the home visitor provided substance-use services. Through Tribal MIECHV, the intense need for substance-use education, assessment, service delivery, and referral in many AI/AN communities is pushing the home-visiting field forward to address this increasingly critical issue for low-income families across the United States and the world.
Monitoring the body condition of free-ranging marine mammals at different life-history stages is essential to understand their ecology as they must accumulate sufficient energy reserves for survival and reproduction. However, assessing body condition in free-ranging marine mammals is challenging. We cross-validated two independent approaches to estimate the body condition of humpback whales (Megaptera novaeangliae) at two feeding grounds in Canada and Norway: animal-borne tags (n = 59) and aerial photogrammetry (n = 55). Whales that had a large length-standardized projected area in overhead images (i.e. whales looked fatter) had lower estimated tissue body density (TBD) (greater lipid stores) from tag data. Linking both measurements in a Bayesian hierarchical model to estimate the true underlying (hidden) tissue body density (uTBD), we found uTBD was lower (-3.5 kg m-3) in pregnant females compared to adult males and resting females, while in lactating females it was higher (+6.0 kg m-3). Whales were more negatively buoyant (+5.0 kg m-3) in Norway than Canada during the early feeding season, possibly owing to a longer migration from breeding areas. While uTBD decreased over the feeding season across life-history traits, whale tissues remained negatively buoyant (1035.3 ± 3.8 kg m-3) in the late feeding season. This study adds confidence to the effectiveness of these independent methods to estimate the body condition of free-ranging whales.
Aerial surveys are often used to monitor wildlife and fish populations, but rarely are the effects on animal behavior documented. For over 30 years, the Kodiak National Wildlife Refuge has conducted low-altitude aerial surveys to assess Kodiak brown bear (Ursus arctos middendorffi) space use and demographic composition when bears are seasonally congregated near salmon spawning streams in southwestern Kodiak Island, Alaska. Salmon (Oncorhynchus spp.) are an important bear food and salmon runs are brief, so decreases in time spent fishing for salmon may reduce salmon consumption by bears. The goal of this study was to apply different and complementary field methods to evaluate the response of bears to these aerial surveys. Ground-based counts at one stream indicated 62% of bears departed the 200m-wide survey zone in response to aerial surveys, but bear counts returned to pre-survey abundance after only three hours. Although this effect was brief, survey flights occurred during the hours of peak daily bear activity (morning and evening), so the three-hour disruption appeared to result in a 25% decline in cumulative daily detections by 38 time-lapse cameras deployed along 10 salmon streams. Bear responses varied by sex-male bears were much more likely than female bears (with or without cubs) to depart streams and female bears with GPS collars did not move from streams following surveys. Although bears displaced by aerial surveys may consume fewer salmon, the actual effect on their fitness depends on whether they compensate by foraging at other times or by switching to other nutritious resources. Data from complementary sources allows managers to more robustly understand the impacts of surveys and whether their benefits are justified. Similar assessments should be made on alternative techniques such as Unmanned Aerial Vehicles and non-invasive sampling to determine whether they supply equivalent data while limiting bear disturbance.
In an effort to characterize food costs in the United States (US)-affiliated Pacific Region, a first-time food cost survey was conducted in March 2014. A market basket survey was developed using an adaptation of the US Department of Agriculture Thrifty Food Plan. Surveys were conducted in the states of Alaska and Hawai'i; Portland, Oregon; the US-affiliated Pacific Islands of American Samoa (American Samoa); Commonwealth of the Northern Mariana Islands; the island of Pohnpei within the Federated States of Micronesia; Guam; Republic of the Marshall Islands; and Republic of Palau. Urban and rural communities were included. Multiple stores in multiple communities were surveyed in each jurisdiction. Food retailers (N = 74) ranged from convenience markets to supermarkets. Not all foods in the market basket survey were available in each of the communities. Inspection of available income data also showed that food costs represented a higher percentage of household income for American Samoa than those of Alaska, Hawai'i, and Portland. Thrifty Food Plan weighted weekly totals for the region ranged from $181.90 to $264.30. Weighting was based on the amount of the item converted to grams required for the Thrifty Food Plan menu. These food costs are significantly higher than those of Portland ($142.00) for the survey period. Protein foods, grains, vegetables, fruit, and dairy were the 5 most costly components, in descending order. Food affordability was assessed by comparing food costs across jurisdictions and examining estimated food costs to reported average jurisdiction incomes. The survey is intended to help inform public health policy and educational programs in the region. A locally adapted food survey would benefit future analyses, regional policy, and educational efforts.
Optimal prostate cancer (PCa) screening strategies will focus on men likely to have potentially lethal disease. Age-specific incidence rates (ASIRs) by modern clinical risk groups could inform risk stratification efforts for screening.
This cross-sectional population study identified all men diagnosed with PCa in Norway from 2014 to 2017 (n = 20,356). Age, Gleason score (primary plus secondary), and clinical stage were extracted. Patients were assigned to clinical risk groups: low, favorable intermediate, unfavorable intermediate, high, regional, and metastatic. Chi-square tests analyzed the independence of Gleason scores and modern PCa risk groups with age. ASIRs for each risk group were calculated as the product of Norwegian ASIRs for all PCa and the proportions observed for each risk category.
Older age was significantly associated with a higher Gleason score and more advanced disease. The percentages of men with Gleason 8 to 10 disease among men aged 55 to 59, 65 to 69, 75 to 79, and 85 to 89 years were 16.5%, 23.4%, 37.2%, and 59.9%, respectively (P
CommentIn: Cancer. 2020 Jun 1;126(11):2718-2719 PMID 32073647
CommentIn: Cancer. 2020 Jun 1;126(11):2718 PMID 32073649
L'activité physique est généralement considérée comme un facteur contribuant de façon significative au vieillissement réussi d'une personne. Certains groupes n'ont cependant pas été suffisamment représentés dans les discussions sur l'activité physique et le vieillissement, particulièrement ceux provenant d'horizons culturels différents. Dans cet article, nous explorons comment les aînés autochtones de l'Alaska perçoivent le rôle de l'activité physique au cours de leur vieillissement et la contribution de l'activité physique au vieillissement réussi. Les entretiens semi-structurés menés auprès de 41 aînés ont montré que l'activité physique n'était pas seulement perçue comme une responsabilité personnelle en vue du maintien d'une bonne santé lors du vieillissement, mais aussi comme un moyen de résister à l'opinion répandue voulant que les personnes âgées soient dans une phase de déclin. Pour ces aînés, être physiquement actif, peu importe l'âge, était vu comme un moyen pour améliorer ou maintenir leur état physique, mental, émotionnel ou spirituel, et permettrait de participer aux activités de subsistance qui sont rattachées à leur culture et aux rôles ancestraux qui leur sont reconnus.
Physical activity is widely considered to be a significant contributing factor to how “successfully” one ages. There are, however, certain groups whose voices have not been widely heard in discussions around physical activity and aging, particularly those from diverse cultural backgrounds. In this research, we explored how Alaska Native Elders perceive the role of physical activity as they age and its contribution to successful aging. Based on semi-structured interviews with 41 Elders, the results show that engaging in physical activity was not just seen as a personal responsibility to maintain health and age successfully, but also as a way to resist Western society’s dominant view of older adults as deteriorating and declining by being physically active regardless of age; to improve or maintain their physical, mental, emotional, and spiritual health; and/or to enable them to continue participating in subsistence activities that are rooted in their culture and traditional roles as Elders.